In this work, the distributions of radionuclides activity as well as radon concentrations in selected rock samples collected from Sinai-Egypt were investigated. Radionuclides distribution, 238U, 232Th and 40K, in rock samples, which were gathered from Um-Bogma region, was calculated by HPGe detector. Also, radon concentration has been measured by using (SSNTD) CR-39. Using empirical equations, the concentration of 222Rn emitted (226Ra decaying) was computed and compared to the tracks recorded by CR-39. From our data, the average specific activity in Bq kg−1 for 238U, 235U, 234U, 226Ra 232Th and 40K were obtained. Measured radon concentrations as generated alpha tracks owing to 222Rnm (measured radon) were compared to occurring 222Rnp (predicted radon) as 226Ra alpha decay to determine measured radon loss in natural samples taken from Sinai, Egypt. The geological structure appears to be the main factor affecting detected radon concentration and results shows that radon emanation was influenced by the rock type.